1. Field of the Invention
The present invention relates to apparatus and method for storing and transferring payloads and propellants in space.
2. Description of the Related Art
The transportation of cargo and propellant mass between locations in space and maintaining a support platform in orbit is expensive. High costs create a barrier to the commercial transportation hardware development for space and to the investment of private capital in technically viable space transportation ventures. Part of this high cost is the expense caused by combining unmanned and manned cargo on the same type of space vehicle and requiring the safety and reliability to be the same for both classes of mass transported. Another reason for costs higher than necessary is the previous practice of using the same vehicle to transport mass in each of transportation cycles beyond the earth's surface instead of transferring mass, payloads and propellant from one vehicle to another as the requirements change. For example, the launch from earth's surface required a vehicle capable of traveling through the earth's atmosphere and also capable of using attitude control systems in the vacuum of space. Historically, these different conditions were satisfied by one vehicle. In a mature Space Exploration Initiative (SEI) transportation systems with separate transportation cycles on earth changing from ocean travel to land transportation would require a change in vehicle types from water requirements to land requirements. The resulting transfer location became a harbor or transportation node with a point of commerce created and various vehicle types obtained transportation related services including specialized cargo and fuel transfer hardware.
Rocket propelled space vehicles transport cargo outside the proximity of the Earth in airless space. Such vehicles may, for example, start a trip from Earth orbit and travel to the surface of the Moon. Such trips use large amounts of propellants, requiring the use of enormous multi-stage rockets. Such rockets may be similar to the Saturn first stage of the Apollo project, which landed the first man on the Moon more than 30 years ago. The longer the trip the more onboard propellant must be transported and the space vehicles grow to a size that is difficult to finance. On mature transportation cycles on earth fuel and cargo transfer services are aided by fuel stations along the road and container cranes to transfer cargo. Innovation in propellant and cargo transfer services is required for space transportation.
Rendezvousing, docking and transferring payloads between space vehicles was performed more than forty years ago in the Apollo program with the lunar orbit transfer of humans from a transport vehicle to a lunar lander vehicle in lunar orbit and saved both propellant and vehicle mass. More recently between shuttles and the International Space Station. For example, in the Apollo program the astronauts had to transferred humans and cargo to/from the lunar lander to the command module in lunar orbit. Today the procedures have been refined and are used, for example, between the Russian Soyuz and the International Space Station. In such conventional systems, the actual transfer of cargo is performed by people after docking of the vehicles and opening of a hatch. However, the automatic transfer of cargo between two vehicles in space, such as unmanned space vehicles, is a more complex operation which been slow to mature in conventional manned and unmanned systems. Accordingly, the transfer of payloads between vehicles in space is currently a labor intensive and inefficient operation. Eventually, mature transportation cycles will emerge space cargo and human transfer and support services will be separated and each will become automated allowing an acceleration in the transportation maturing process and a potential reduction in costs. Cargo and payloads will be transferred from one vehicle to another vehicle with a different design, much the way a ship transfers cargo from a ship to a truck or rail car at a port. If the cargo were transferred automatically, then it would accelerate the maturing process, but maybe more expensive given the cost of labor on earth. The modern container ship, for example, is unloaded in a near automatic manner with a single crane operator compared to a cargo net and gang of men fifty years ago. Now the cost of labor in space is expensive and the unmanned cargo transfer is likely to be automatic as well as the ship that carries the unmanned cargo. The ratio of human cargo (1%) and unmanned cargo (99%) is significantly great to make it an issue in the design process, because the cost of a manned or crewed vehicle is much greater than an unmanned vehicle.